US 6,635,217 B1 · Containers

Abstract

A container is made in two stages from material such as thermoplastics that is deformable when heated. In the first stage a preform (1) is injection moulded, the mould parts easily releasing a tubular body (2) with a closed end. In the second stage the still heated preform (1) is blow moulded, possibly with some preliminary mechanical stretching, the blow pin being applied to the open end. The closed end of the body is stretched over a multi-part section (7, 8) of the mould which shapes the base of the container into an indent with an undercut formation, the cross section being generally omega-shaped. The multi-part mould section has a central tapered core (8) surrounded by an array of segments (7), the core (8) being fully inserted to spread the segments (7) for moulding, and being retracted to allow the segments (7) to close up and release the container after moulding. The divisions (12) between segments (7) produce ribs in the indent which provide added strength.

Claims9

Dependent claims

A method of making a container with an undercut re-entrant base, the material of the container being susceptible to deformation when heated, the method comprising the steps of:

expanding the base portion of an embryo container, at an elevated temperature, against a multi-part mould having at least three segments surrounding a tapered core;
moving the core to wedge the segments laterally from a closely packed array to a mutually spread array thereby to form the undercut re-entrant base;
retracting the core, returning the segments to a closely packed array and releasing the container therefrom;
wherein the container in both embryo and finished form is substantially a body of revolution, the core is co-axial therewith, and the segments are all similar with radial sides abutting when close-packed.

1 more element

Dependencies are inferred from the claim text.

Containers

Life of this patent

Containers

Life of this patent

Abstract

Claims9